The communications industry is rapidly changing to adjust to emerging technologies and ever increasing customer demand. This customer demand for new applications and increased performance of existing applications is driving communications network and system providers to employ networks and systems having greater speed and capacity (e.g., greater bandwidth). In trying to achieve these goals, a common approach taken by many communications providers is to use packet switching technology. Increasingly, public and private communications networks are being built and expanded using various packet technologies, such as Internet Protocol (1P).
Spatial Reuse Protocol (SRP) is one type of networking protocol for communicating packet traffic over a bi-directional ring, and provides a technique for more efficient ring usage as compared to regular packet over SONET. SRP is described in “The Cisco SRP MAC Layer Protocol,” RFC 2892, IETF (August 2000), which is hereby incorporated by reference. Using SRP, only traffic which is destine for the current node is processed by its layer 3 and up protocol processing mechanisms. All other traffic transits further on the ring until it reaches its destination. Because the each node needs to be able to insert its own traffic on the ring, each node includes a transit buffer (TB) which holds transit traffic (e.g., those packets received which are not destined for itself) for a short duration, allowing a node to insert traffic on the ring. SRP provides fair distribution of low priority traffic; however the high priority traffic is not controlled by fairness algorithm. This means that a high priority transit buffer can be overflowed. For example, if the previous node sends one hundred percent high priority traffic which is transit for current node and the media speed of previous node is higher than a speed of a current node. For example, the speed of a SONET link may vary of +/−20 ppm. If the a node is transmitting out a −20 ppm link and is receiving one hundred percent high priority traffic from a previous node at a rate of +20 ppm, then the high priority transit buffer fills at a rate of +40 ppm of the SONET clock and eventually the buffer will overflow.
A known prior attempt at solving this overflow problem was to periodically stall or stop traffic from being taken from the transit buffer of a node that sent traffic over a faster link. In this manner, a time gap was induced by the transit buffer circuitry. However, buffering is typically used by the link transmission components, which removed or reduced such time gap, and thus, the overflow condition still could be created. New methods and apparatus are desired which may reduce or eliminate the overflow condition.